Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils
Reexamination Certificate
1998-06-29
2001-03-13
Eldred, J. Woodrow (Department: 3641)
Aeronautics and astronautics
Aircraft sustentation
Sustaining airfoils
C244S201000, C244S218000, C244S219000
Reexamination Certificate
active
06199796
ABSTRACT:
The present invention relates to a pneumatic, so-called adaptive wing, i.e. inflated by compressed air and modifiable in form by the applied effects of compressed air in accordance with the preamble to claim
1
.
Pneumatic wings as such have been variously proposed and are known, for example from two groups of documents:
the first group describes wing structures, which are built up from a plurality of tubular elements: U.S. Pat. No. 3,473,761, U.S. Pat. No. 4,725,021 and U.S. Pat. No. 3,957,232;
the wing structures of the other group are kept in shape by distance-threads and textile straps (so-called “webs”): DE 949 920, U.S. Pat. No. 2,886,265, U.S. Pat. No. 3,106,373 and U.S. Pat. No. 3,481,569.
Pneumatic adaptive wings are not known from the Patent literature.
Pneumatic wings in themselves fulfil a rational technical need only if they provide advantages in respect of weight, production costs, simplicity of handling and flight characteristics over other, non-pneumatic, forms of construction and can also be folded in non-operational circumstances; these named advantages do not need to be present in all the quoted areas; an overall evaluation should, however, make a pneumatic wing appear advantageous. If we evaluate the documents in the first group, then a pneumatic wing according to U.S. Pat. No. 3,473,761 appears heavy, complicated and expensive to produce and, which weighs most heavily, is ill suited to solve the static problems of a wing. The wing according to U.S. Pat. No. 3,957,232 is—in contrast to the previous example—constructed of pressure tubes with a large cross section. The proposed device is however not suitable for creating the necessary circulation or surface tension in the wing skin, or suffers from deformations, which are not shown or mentioned. If, however, one takes these deformations of the pressure tubes into account, then it can be seen that the construction is heavy and, in the loaded method of construction, not very stable. In the third description, only a spar structure is constructed from pneumatic elements; the remainder of the wing receives its shape from sail battens.
The wings or profiles, which are known from the second group of documents, are basically constructed of under and over skins and the strings or webs which connect the two elements. The solution known from U.S. Pat. No. 3,106,373 differs from the others in so far as the whole wing envelope comprises an airtight distance web, which is bent and glued into the required shape. The problems of this group comes out most clearly from DE 949 920.
The wing profile is there symmetrical. The necessary aerodynamic lift (c
A
) for a wing—whether it be a carrying wing or rotor blade—can only be generated by the adjustment angle. The wing profiles shown in the other publications in no case assume the shapes represented under pressure: in the region where strings or webs terminate in the wing skin, pressure and tensile forces act together and give the wing skin its final shape. Especially the profile known from U.S. Pat. No. 2,886,265, but to a certain extent the others also, essentially assume under pressure the shape known from DE 949 920, with disappearing c
A
. Added to this a pneumatic wing is poorly suited for the attachment of control cables or rods, especially for moving the aileron. All the proposed ailerons are entirely copied from those of rigid wing structures and do not represent any technical advance.
What is lacking in all the quoted documents is the intrinsic technical knowledge of how to produce the overall profile, which poses the question as to whether such profiles were ever built, not to mention whether they were then flown.
The problem which is to be addressed by the present invention, exists on the one hand in the production of a pneumatic wing with a prescribed profile and a predetermined lift coefficient c
A
, with an attached pneumatic aileron which avoids control wires or rods, and on the other, the wing profile, as a whole or in part, should be modified and optimised with respect to the flight speed by the application of elements inflated with compressed air. The usable speed region is thus increased overall.
REFERENCES:
patent: 2886265 (1959-05-01), Ritter et al.
patent: 2979827 (1961-04-01), Ross
patent: 3106373 (1963-10-01), Bain et al.
patent: 3473761 (1969-10-01), Chutter
patent: 3481569 (1969-12-01), Bell
patent: 3957232 (1976-05-01), Sebrell
patent: 4261534 (1981-04-01), Roselli
patent: 4725021 (1988-02-01), Priddy
patent: 5474257 (1995-12-01), Fisher et al.
patent: 5775249 (1998-07-01), Samuel
patent: 683250 (1994-02-01), None
patent: 949920 (1956-09-01), None
patent: 3707463 (1987-10-01), None
patent: 615112 (1949-01-01), None
patent: 835221 (1960-05-01), None
patent: 2165513 (1984-10-01), None
Kammer Res
Ramseier Otto
Reinhard Andreas
To Frederick E.
Eldred J. Woodrow
Jenkens & Gilchrist, P. C.
Prospective Concepts AG
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